From the Guidelines
Radiographic signs of pericardial effusion include enlargement of the cardiac silhouette with a "water bottle" appearance on chest X-ray, which occurs when fluid accumulates in the pericardial space surrounding the heart, as described in the 2015 ESC guidelines for the diagnosis and management of pericardial diseases 1. The diagnosis of pericardial effusion is primarily made using echocardiography, which shows an echo-free space between the pericardium and epicardium, with the size of the effusion qualitatively assessed by the end-diastolic distance of the echo-free space between the epicardium and parietal pericardium 1. Some key points to consider in the diagnosis of pericardial effusion include:
- Enlargement of the cardiac silhouette with a "water bottle" appearance on chest X-ray
- Clear lung fields, unlike in heart failure
- Rapid enlargement of the cardiac silhouette compared to previous films
- Sometimes a "fat pad sign" where a radiolucent line separates the epicardial fat from the pericardial fat
- Increased retrosternal space opacity on lateral views
- Echocardiography remains the gold standard for diagnosis, with CT and MRI providing additional details about the effusion's extent, location, and composition 1. The severity of radiographic changes generally correlates with the volume of fluid present, with at least 250mL typically needed before becoming radiographically apparent, and the haemodynamic tolerance is more related to the rapidity of appearance of the effusion than to its total volume 1. In terms of management, pericardiocentesis is a class I indication for cardiac tamponade, and systemic antineoplastic treatment, pericardiocentesis, and intrapericardial instillation of cytostatic/sclerosing agents may be recommended for large suspected neoplastic pericardial effusion without tamponade 1.
From the Research
Radiographic Signs of Pericardial Effusion
- Pericardial effusion is defined by an increase in the physiological amount of fluid within the pericardial space 2
- The diagnosis of pericardial effusion can be evaluated using various imaging techniques, including chest X-ray, electrocardiogram, transthoracic echocardiography, computed tomography scan, cardiac magnetic resonance imaging, and pericardiocentesis 3
- Echocardiographic evaluation of pericardial effusion is paramount for timely and appropriate diagnosis and management, and includes assessing the quantity and quality of pericardial fluid, collapse of cardiac chambers, respiratory variation of the ventricular diameters, inferior vena cava collapsibility, and flow patterns in atrioventricular valves 2
Echocardiographic Findings
- The core echocardiographic findings of pericardial tamponade consist of:
- a pericardial effusion
- diastolic right ventricular collapse (high specificity)
- systolic right atrial collapse (earliest sign)
- a plethoric inferior vena cava with minimal respiratory variation (high sensitivity)
- exaggerated respiratory cycle changes in mitral and tricuspid valve in-flow velocities as a surrogate for pulsus paradoxus 4
- Other echocardiographic clues to tamponade include Doppler flow velocity paradoxus, and inferior vena cava phlethora 5
Imaging Modalities
- CT and MRI may be employed and may be more accurate than echocardiography in evaluating pericardial effusion 5
- Point-of-care ultrasound (POCUS) may be used to evaluate pericardial effusion, but should be interpreted with caution to avoid misdiagnosis of tamponade 4
- Multimodality imaging may have niche functions in managing pericardial effusion and cardiac tamponade 6